Microbiology
- Member of Chlamydia Genus (Family: Chlamydiaceae)
- Characteristics: small, obligate intracellular, Gram-negative organism
- Major Outer Membrane Protein (MOMP): functions as adhesin for binding to epithelial cells
- Lipopolysaccharide (LPS): functions to elicit immune response to organism
- Life Cycle
- Inactive Form: inactive elementary bodies attach to and penetrate into cells -> changing into the active form (reticulate bodies) within 6-8 hrs
- Active Form: active reticulate bodies form large intracellular inclusions
- Reticulate bodies reorganize into elementary bodies and within 2-3 days, cell ruptures and releases newly formed elementary bodies
- Antibiotic Resistance: appears to be very rare
Physiology
- Immunity to Chlamydia Trachomatis Infection: typically not long-lasting -> this may explain persistent or recurrent infections
- The intracellular location of Chlamydia Trachomatis infection eliminates the need for rapid evolution of cell surface components that might contribute to antibiotic resistance
- As elementary bodies are relatively inert, opportunities for replication and the generation of antibiotic resistance mutations are limited
- These features may explain the relatively asymptomatic nature of many Chlamydia Trachomatis infections
Diagnosis
Nucleic Acid Amplification Test (NAAT)
- Indications: second generation tests are indicated to detect both Neisseria Gonorrhoeae and Chlamydia Trachomatis in males/females with or without symptoms
- Availability: commercially available from multiple manufacturers (Roche, etc)
- Technique: PCR amplification, strand displacement amplification (SDA), or transcription-mediated amplification (TMA) of organism DNA/RNA in sample
- Technique can theoretically detect as little as one organism per samples (the detection threshold of culture is approximately 1000 organisms per sample)
- Sensitivity of various amplification methods varies
- Optimal Specimen Type
- Male: first void urine sample
- Perform as well or better than urethral swabs
- Female: vaginal swab
- Vaginal swabs perform as well as cervical swabs (although cervical swabs may be substituted in cases when pelvic exam is performed)
- Self-collected vaginal swabs are equivalent in sensitivity/specificity to clinician-collected vaginal swabs
- Female urine specimens are 10% less effective than vaginal swabs for detection of Neisseria Gonorrhoeae (possibly related to the presence of urine inhibitory substances which may interfere with NAAT)
- Female “clean catch” urine (if being performed at the same time) requires external cleansing of the urethra, which will impede optimal NAAT testing of urine -> therefore, NAAT of female urine should be performed using first void urine without external cleansing prior to collection
- Cost-Effectiveness: cost effective in preventing sequelae of Neisseria Gonorrhoeae and Chlamydia Trachomatis infections
- Cross-Reactivity with Non-Gonococcal Neisseria Species: none
- Advantages of NAAT Over Urethral Swab Culture
- Higher Sensitivity (100%) and Equal Specificity (99%) Than Urethral Swab Culture
- Non-Invasive Collection Method: requires only urine to perform, rather than a urethral swab
- Single Test Can Be Employed for Both Organisms
- Faster Test Turnaround Time Than Urethral Swab Culture
- Advantages of NAAT Over Other Molecular Testing Methods
- NAAT’s are preferred over direct fluorescence antibody testing, ELISA’s, nucleic acid hybridization tests due to their superior sensitivity/specificity
- Disadvantages of NAAT
- NAAT does not enable determination of antibiotic sensitivities: therefore, cultures are still required in cases where antibiotic resistance is suspected
- NAAT does not provide results at the point of care (specimens must be processed in the lab)
- NAAT is expensive
- Use of NAAT with Non-Genital Body Specimens
- NAAT have higher sensitivity than culture to detect Chlamydia Trachomatis in oropharyngeal or rectal samples in males with have intercourse with other males: however, this use is not FDA-approved and needs to be validated in terms of performance at the local lab/clinical site
Urinalysis with Urine Culture
- Specimen: first void urine specimen is required
- Urination within 2 hrs of exam should be avoided, as it may impair the ability to detect organisms
- Criteria: >10 WBC per hpf on first void urine is consistent with urethritis
- Criteria: positive leukocyte esterase (on dipstick) on first void urine is consistent with urethritis
Urethral Swab with Culture
- Used historically to diagnose Neisseria Gonorrhoeae and Chlamydia Trachomatis infections: however, NAAT above is now the preferred diagnostic method to detect these organisms
- Culture is currently the only means of detecting Mycoplasma Genitalium and Ureaplasma Urealyticum infections
- DNA-based testing methods (with 97% sensitivity) for these organisms have been developed, but are not commercially available yet
- Criteria: >5 neutrophils per hpf indicates presence of urethritis
- Disadvantages
- Urethral swab procedure is uncomfortable
Other Testing
- Herpes Simplex Virus (HSV) Culture and PCR: indicated in patients who have genital ulcer(s)
- Affirm PCR Assay: indicated only in female cases to detect the 3 major causes of bacterial vaginosis (Candida, Gardnerella, and Trichomonas)
- Utilizes vaginal/cervical swab
- HIV Test: usually indicated in cases of suspected sexually-transmitted infection, due to possibility of co-infection with HIV
- RPR: usually indicated in cases of suspected sexually-transmitted infection or genital ulcer(s), due to possibility of co-infection with syphilis
Clinical Manifestations
Genito-Urinary Manifestations
- Epididymitis (see Epididymitis, [[Epididymitis]])
- Lymphogranuloma Venereum (LGV) (Climatic Bubo, Durand–Nicolas–Favre Disease, Poradenitis Inguinale, Strumous Bubo)
- Urethritis (see Urethritis, [[Urethritis]])
Ophthalmalogic Manifestations
Pulmonary Manifestations
Other Manifestations
Treatment
References